The Role of Greenhouse Gases in the Kashkan River's Discharge Fluctuation

The aim of this research is to investigate the correlation of greenhouse gases-carbon dioxide and methane - as elements of global warming on the Kashkan River’s discharge values. The data used in this study consist of seasonal and annual data of greenhouse gases and Kashkan River’s debby between 1984 to 2010, using Pearson correlation coefficient, linear regression and Man-Kendal graphic method. The results show a strong negative correlation between the rate of global warming and the Kashkan River. This process has been intensified over the last 15 years, and from 1995 onwards the Kashkan River’s discharge has faced a sharp decline. Study of the changes in the annual runoff discharge strongly indicates an inverse relationship between global warming and Kashkan River flow; so that 2/55 of the annual discharge decrease in Kashkan River’s basin is the result of the global warming. Global warming has also affected the seasonal scale of Kashkan River’s discharge. The results show a reduction of discharge by 7/47 in summer, 6/45 in autumn, 38 percent in spring and 1/33 percent in winter. Finally, the use of exponential regression model predicted that if the global warming continues with the same scale, the average annual flow of the river will be below 10 cubic meters per second in the next 30 years, i.e. is till 2040.